Releases
Current Releases
Note: This section is in need of some serious love. It depends on a set of templates that appear to be unmaintained. Please use the RapidRelease page instead
Standard support
Based on Gecko 147
Firefox 147.0.4
Based on Gecko 147
Based on Gecko 147
Released on 2026-02-16
SeaMonkey 2.144
Based on Gecko 147
Based on Gecko 147
Released on 2015-09-26
Based on Gecko 38
Thunderbird 60.87
Based on Gecko 60
Based on Gecko 60
Released on 2026-02-16
Based on Gecko 28
Firefox OS 1.3
Based on Gecko 28
Based on Gecko 28
Released on 2014-03-17
Extended support
Based on Gecko 60
Firefox 60.87.0esr
Based on Gecko 60
Based on Gecko 60
Released on 2026-01-13
Upcoming Releases
NOTE: The dates listed in this section refer to the date of the code merge, not the date of release. See the branch migration calendar for more information.
Based on Gecko 148
Firefox 148
Based on Gecko 148
Based on Gecko 148
Currently in BETA channel
Moves to RELEASE week of February 24, 2026
Moves to RELEASE week of February 24, 2026
Thunderbird 148
Based on Gecko 148
Based on Gecko 148
Currently in BETA channel
SeaMonkey 2.145
Based on Gecko 148
Based on Gecko 148
Currently in BETA channel
Moves to RELEASE week of February 24, 2026
Moves to RELEASE week of February 24, 2026
Based on Gecko 54
Firefox 54
Based on Gecko 54
Based on Gecko 54
Currently in AURORA channel
Moves to BETA week of February 24, 2026
Moves to BETA week of February 24, 2026
Thunderbird 54
Based on Gecko 54
Based on Gecko 54
Currently in EARLYBIRD channel
Moves to BETA week of February 24, 2026
Moves to BETA week of February 24, 2026
SeaMonkey 2.51
Based on Gecko 54
Based on Gecko 54
Currently in AURORA channel
Moves to BETA week of February 24, 2026
Moves to BETA week of February 24, 2026
Based on Gecko 149
Firefox 149
Based on Gecko 149
Based on Gecko 149
Currently in NIGHTLY channel
Moves to BETA week of February 24, 2026
Moves to BETA week of February 24, 2026
Thunderbird 149
Based on Gecko 149
Based on Gecko 149
Currently in DAILY channel
Moves to BETA week of February 24, 2026
Moves to BETA week of February 24, 2026
SeaMonkey 2.146
Based on Gecko 149
Based on Gecko 149
Currently in NIGHTLY channel
Moves to AURORA week of February 24, 2026
Moves to AURORA week of February 24, 2026
B2G Releases
Firefox OS 1.4
Based on Gecko 30
Based on Gecko 30
Released on ??
Firefox OS 2.0
Based on Gecko 32
Based on Gecko 32
Currently in BETA channel
Moves to RELEASE week of ??
Moves to RELEASE week of ??
Firefox OS 2.1
Based on Gecko 34
Based on Gecko 34
Currently in AURORA channel
Moves to BETA week of ??
Moves to BETA week of ??
Firefox OS 2.2
Based on Gecko 37
Based on Gecko 37
Currently in NIGHTLY channel
Moves to AURORA week of ??
Moves to AURORA week of ??
Previous Releases
More details of the RapidRelease Calendar
2015
The full list of releases is on mozilla.org, but you will need to click through to the notes for each for each release to find out the dates.
| Release | Date | Notes |
|---|---|---|
| SeaMonkey 2.38 | September 26 | Release Notes |
| Firefox 38.3.0 esr | September 22 | Release Notes |
| SeaMonkey 2.35 | September 3 | Release Notes |
| Firefox 40.0.3 | August 27 | Release Notes |
| Firefox 38.2.1 esr | August 27 | Release Notes |
| Thunderbird 38.2.0 | August 14 | Release Notes |
| Firefox 40.0.2 | August 13 | Release Notes |
| Firefox 38.2.0 esr | August 11 | Release Notes |
| Firefox 40 | August 11 | Release Notes |
| Firefox 39.0.3 | August 6 | Release Notes |
| Thunderbird 31.8.0 | July 17 | Release Notes |
| Thunderbird 38.1.0 | July 9 | Release Notes |
| Firefox 39 | July 02 | Release Notes |
| Firefox 38.1.0 esr | July 02 | Release Notes |
| Thunderbird 38.0.1 | June 11 | Release Notes |
| Firefox 38.0.5 | June 2 | Release Notes |
| Thunderbird 31.7.0 | May 12 | Release Notes |
| Firefox 38.0.1 | May 14 | Release Notes |
| Firefox 38 | May 12 | Release Notes |
| Firefox 37.0.2 | April 20 | Release Notes |
| Firefox 37.0.1 | April 3 | Release Notes |
| Thunderbird 31.6.0 | March 31 | Release Notes |
| Firefox 37 | March 31 | Release Notes |
| SeaMonkey 2.33.1 | March 23 | Release Notes |
| Firefox 36.0.4 | March 21 | Release Notes |
| Firefox 36.0.3 | March 20 | Release Notes |
| SeaMonkey 2.33 | March 10 | Release Notes |
| Firefox 36.0.1 | March 5 | Release Notes |
| Thunderbird 31.5.0 | February 24 | Release Notes |
| Firefox 36.0 | February 24 | Release Notes |
| SeaMonkey 2.32 | January 13 | Release Notes |
| Thunderbird 31.4.0 | January 13 | Release Notes |
| Firefox 35.0 | January 13 | Release Notes |
2014 and earlier
For releases prior to 2015, see the archive.
Other Links
This is a page for tracking in-progress releases. For maintenance releases, we use a general checklist to ensure we don't miss anything.
- perhaps you'd like to see who release drivers for various releases are?
- or perhaps you'd like to learn more about the priority rankings we assign to releases?
- you might even wonder how we use flags to manage our releases?
- or what branches exist and when they branched?
- perchance you're confused about update terminology?
- maybe you'd like to know about our various branch support levels?
- perhaps you want to see the RapidRelease Calendar for future aurora merges, beta merges, and releases?
- maybe you are interested in checking the Feature Release Tracker for upcoming features?